U.S. patent application number 13/208031 was filed with the patent office on 2012-08-16 for electrical power storage system using hydrogen and method for storing electrical power using hydrogen.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Daisuke Horikawa, Yoshiyasu Ito, Tsuneji Kameda, Shigeo Kasai, Kentaro Matsunaga, Shoko SUYAMA, Yasuo Takagi, Kazuya Yamada, Masato Yoshino.
Application Number | 20120208100 13/208031 |
Document ID | / |
Family ID | 42561679 |
Filed Date | 2012-08-16 |
United States Patent
Application |
20120208100 |
Kind Code |
A1 |
SUYAMA; Shoko ; et
al. |
August 16, 2012 |
ELECTRICAL POWER STORAGE SYSTEM USING HYDROGEN AND METHOD FOR
STORING ELECTRICAL POWER USING HYDROGEN
Abstract
In one embodiment, an electrical power storage system using
hydrogen includes a power generation unit generating power using
hydrogen and oxidant gas and an electrolysis unit electrolyzing
steam. The electrical power storage system includes a hydrogen
storage unit storing hydrogen generated by the electrolysis and
supplying the hydrogen to the power generation unit during power
generation, a high-temperature heat storage unit storing high
temperature heat generated accompanying the power generation and
supplying the heat to the electrolysis unit during the
electrolysis, and a low-temperature heat storage unit storing
low-temperature heat, which is exchanged in the high-temperature
heat storage unit and generating with this heat the steam supplied
to the electrolysis unit.
Inventors: |
SUYAMA; Shoko;
(Kawasaki-shi, JP) ; Ito; Yoshiyasu;
(Yokohama-shi, JP) ; Kasai; Shigeo; (Kamakura-shi,
JP) ; Takagi; Yasuo; (Chigasaki-shi, JP) ;
Kameda; Tsuneji; (Tokyo, JP) ; Matsunaga;
Kentaro; (Tokyo, JP) ; Yoshino; Masato;
(Yokohama-shi, JP) ; Horikawa; Daisuke;
(Yokohama-shi, JP) ; Yamada; Kazuya; (Tokyo,
JP) |
Assignee: |
KABUSHIKI KAISHA TOSHIBA
|
Family ID: |
42561679 |
Appl. No.: |
13/208031 |
Filed: |
August 11, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2010/000905 |
Feb 15, 2010 |
|
|
|
13208031 |
|
|
|
|
Current U.S.
Class: |
429/422 ;
264/29.7; 428/414; 428/448; 523/443; 524/730 |
Current CPC
Class: |
Y02E 60/36 20130101;
C04B 2235/96 20130101; C04B 2235/785 20130101; C04B 2235/5436
20130101; C04B 2237/708 20130101; C04B 2111/00853 20130101; C04B
2235/5445 20130101; H01M 8/0656 20130101; B32B 18/00 20130101; H01M
8/04052 20130101; C04B 2235/77 20130101; C04B 2235/3826 20130101;
C04B 2237/368 20130101; H01M 8/04059 20130101; C04B 2237/086
20130101; C04B 2237/363 20130101; Y02E 60/528 20130101; Y10T
428/31515 20150401; C04B 2237/083 20130101; C04B 2237/365 20130101;
H01M 8/186 20130101; C04B 37/005 20130101; C09J 163/00 20130101;
Y02E 60/366 20130101; Y02E 60/50 20130101; C04B 35/573 20130101;
C04B 2235/786 20130101; C04B 38/0022 20130101; C04B 38/0022
20130101; C04B 35/573 20130101; C04B 38/0054 20130101; C04B 38/0074
20130101 |
Class at
Publication: |
429/422 ;
524/730; 523/443; 428/414; 428/448; 264/29.7 |
International
Class: |
H01M 8/06 20060101
H01M008/06; C01B 31/36 20060101 C01B031/36; C08K 3/34 20060101
C08K003/34; B32B 18/00 20060101 B32B018/00; C08L 71/00 20060101
C08L071/00; C08L 63/00 20060101 C08L063/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 16, 2009 |
JP |
P2009-032494 |
Mar 5, 2009 |
JP |
P2009-051558 |
Feb 9, 2010 |
JP |
P2010-026457 |
Claims
1. An electrical power storage system using hydrogen, comprising: a
power generation unit generating power using hydrogen and oxidant
gas; an electrolysis unit electrolyzing steam to generate hydrogen;
a hydrogen storage unit storing hydrogen generated by the
electrolysis and supplying the hydrogen to the power generation
unit during power generation; a high-temperature heat storage unit
storing first heat generated accompanying the power generation and
supplying the first heat to the electrolysis unit during the
electrolysis; and a low-temperature heat storage unit storing
second heat, which is exchanged in the high-temperature heat
storage unit and is lower than the temperature of the first heat
stored in the high-temperature heat storage unit, and generating
with the second heat the steam supplied to the electrolysis
unit.
2. The electrical power storage system according to claim 1,
wherein the power generation unit and the electrolysis unit are
formed of a solid electrolyte fuel cell comprising a solid-oxide
electrolyte and combining a fuel cell and a steam electrolysis
cell, and are structured to be operable by switching between
respective operating modes of the power generation unit and the
electrolysis unit over time.
3. The electrical power storage system according to claim 1,
wherein the power generation unit is formed of a solid electrolyte
fuel cell comprising a solid-oxide electrolyte, and the
electrolysis unit is formed of a steam electrolysis cell comprising
a solid-oxide electrolyte and being separate from the solid
electrolyte fuel cell.
4. The electrical power storage system according to claim 1,
wherein at least one of the high-temperature heat storage unit and
the low-temperature heat storage unit comprises a plurality of
capsules, a heat storage material encapsulated in the plurality of
capsules and having a melting point to melt when storing heat and
solidify when releasing heat, and a heat storage container
accommodating the plurality of capsules and forming flow paths of a
heat medium fluid flowing around the capsules.
5. The electrical power storage system according to claim 4,
wherein the capsules are formed of at least one selected from a
silicon carbide sintered body, a silicon carbide-silicon composite
sintered body, a silicon carbide-based long fiber composite
material, a boron carbide sintered body, a silicon nitride sintered
body, a boron nitride sintered body, and graphite.
6. The electrical power storage system according to claim 4,
wherein the capsules have a first ceramic member and a second
ceramic member, at least one of which has a container shape, and
the first ceramic member and the second ceramic member are joined
via a joining layer in a state that the heat storage material is
inserted therebetween, the joining layer formed of a ceramic layer
formed by firing a ceramic precursor, a carbon layer formed by
firing a carbon adhesive, or a silicon layer formed by firing a
silicon brazing material.
7. The electrical power storage system according to claim 4,
wherein the capsules have a first ceramic member and a second
ceramic member, at least one of which has a container shape, and
the first ceramic member and the second ceramic member are joined
via a joining layer in a state that the heat storage material is
inserted therebetween, the joining layer formed of a silicon
carbide-silicon composite body having silicon carbide particles and
a silicon phase which exists continuously in interstices among the
silicon carbide particles.
8. The electrical power storage system according to claim 7,
wherein the silicon carbide-silicon composite body forming the
joining layer is formed by impregnating a porous body having first
silicon carbide particles and carbon with molten silicon, causing
the carbon to react with the molten silicon to generate second
silicon carbide particles, and leaving part of the molten silicon
as the silicon phase.
9. The electrical power storage system according to claim 8,
wherein the porous body is formed by disposing a viscous material,
containing a silicon carbide powder having a mean particle diameter
in the range of 0.5 .mu.m to 5 .mu.m, a carbon powder having a mean
particle diameter in the range of 0.3 .mu.m to 3 .mu.m, and a room
temperature setting resin and a curing agent thereof, between the
first ceramic member and the second ceramic member, curing the room
temperature setting resin under room temperature to make a
solidified body, and heat treating the solidified body to carbonize
a cured product of the room temperature setting resin.
10. The electrical power storage system according to claim 9,
wherein the volume ratio of the silicon carbide powder to all the
powder components in the viscous material is in the range of 18% to
60%, and the total mass ratio of the silicon carbide powder and the
carbon powder is in the range of 29% to 55% of the entire viscous
material.
11. The electrical power storage system according to claim 1,
wherein the high-temperature heat storage unit comprises a heat
storage material formed of at least one selected from sodium
chloride, potassium chloride, magnesium chloride, calcium chloride,
lithium fluoride, sodium fluoride, lithium carbonate, sodium
carbonate, potassium carbonate, and lithium hydroxide.
12. The electrical power storage system according to claim 1,
wherein the low-temperature heat storage unit comprises a heat
storage material formed of at least one selected from xylitol,
erythritol, mannitol, sorbitol, alditol, and urea.
13. The electrical power storage system according to claim 1,
wherein the low-temperature heat storage unit comprises a heat
storage material formed of at least one selected from aluminum
chloride, iron chloride, lithium hydroxide, sodium hydroxide,
potassium hydroxide, sodium nitrite, lithium nitrate, sodium
nitrate, and potassium nitrate.
14. A method for storing electrical power using hydrogen,
comprising: generating power using hydrogen and oxidant gas;
electrolyzing steam to generate hydrogen; storing hydrogen
generated by the steam electrolyzing, so as to supply the hydrogen
to the power generating; storing first heat generated accompanying
the power generating, so as to supply the first heat to the steam
electrolyzing; and storing second heat, which is exchanged in the
first heat storing and is lower than the temperature of the first
heat, so as to generate the steam supplied to the steam
electrolyzing.
15. A ceramic joining material, comprising: a mixture containing a
silicon carbide powder having a mean particle diameter in the range
of 0.5 .mu.m to 5 .mu.m, a carbon powder having a mean particle
diameter in the range of 0.3 .mu.m to 3 .mu.m, and a room
temperature setting resin having viscosity and adhesiveness; and a
curing agent of the room temperature setting resin which cures the
mixture, wherein the volume ratio of the silicon carbide powder to
all the powder components in the joining material is in the range
of 18% to 60%.
16. The ceramic joining material according to claim 15, wherein the
total mass ratio of the silicon carbide powder and the carbon
powder is in the range of 29% to 55% of the entire joining
material.
17. The ceramic joining material according to claim 15, wherein the
room temperature setting resin is an epoxy resin or a phenol resin
having a room temperature setting property.
18. The ceramic joining material according to claim 15, wherein the
joining material is used for joining at least two ceramic
bodies.
19. The ceramic joining material according to claim 15, wherein the
joining material is used for repairing a ceramic body.
20. The ceramic joining material according to claim 18, wherein the
ceramic bodies are at least one selected from a silicon
carbide-carbon composite molded body, a silicon carbide-silicon
composite sintered body, a silicon carbide sintered body, a silicon
nitride sintered body, and graphite.
21. A manufacturing method of a ceramic composite member,
comprising: disposing between a plurality of ceramic bodies or on a
part of a ceramic body, a viscous material prepared by mixing a
mixture containing a silicon carbide powder having a mean particle
diameter in the range of 0.5 .mu.m to 5 .mu.m, a carbon powder
having a mean particle diameter in the range of 0.3 .mu.m to 3
.mu.m, and a room temperature setting resin having viscosity and
adhesiveness, with a curing agent of the room temperature setting
resin which cures the mixture; curing the room temperature setting
resin to make a shaped product having a solidified body of the
viscous material adhered to the ceramic bodies; heat treating the
shaped product to carbonize a cured product of the room temperature
setting resin, so as to cause the solidified body of the viscous
material to be porous; and producing a ceramic composite member
having a silicon carbide-silicon composite body formed by
impregnating at least the porous solidified body of the viscous
material with molten silicon, causing carbon components in the
solidified body to react with the molten silicon, and leaving part
of the molten silicon as a silicon phase.
22. The manufacturing method of the ceramic composite member
according to claim 21, wherein the volume ratio of the silicon
carbide powder to all the powder components in the viscous material
is in the range of 18% to 60%.
23. The manufacturing method of the ceramic composite member
according to claim 21, wherein the total mass ratio of the silicon
carbide powder and the carbon powder is in the range of 29% to 559%
of the entire viscous material.
24. The manufacturing method of the ceramic composite member
according to claim 21, wherein the silicon carbide-silicon
composite body comprises first silicon carbide particles based on
the silicon carbide powder, second silicon carbide particles
generated by reaction between the carbon components and the molten
silicon, and the silicon phase existing continuously in interstices
among the first and second silicon carbide particles.
25. The manufacturing method of the ceramic composite member
according to claim 21, wherein the ceramic body is formed of at
least one selected from a silicon carbide-carbon composite molded
body, a silicon carbide-silicon composite sintered body, a silicon
carbide sintered body, a silicon nitride sintered body, and
graphite.
26. The manufacturing method of the ceramic composite member
according to claim 21, wherein the plurality of ceramic bodies are
joined via the silicon carbide-silicon composite body.
27. The manufacturing method of the ceramic composite member
according to claim 21, wherein the part of the ceramic body is
repaired with the silicon carbide-silicon composite body.
28. The manufacturing method of the ceramic composite member
according to claim 21, wherein a mean pore diameter of the porous
solidified body is in the range of 0.5 .mu.m to 5 .mu.m.
29. The manufacturing method of the ceramic composite member
according to claim 21, wherein a mean diameter of the silicon phase
in the silicon carbide-silicon composite body is in the range of
0.2 .mu.m to 2 .mu.m.
30. A ceramic composite member manufactured by the manufacturing
method of a ceramic composite member according to claim 21.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of prior International
Application No. PCT/JP2010/000905 filed on Feb. 15, 2010, which is
based upon and claims the benefit of priority from Japanese Patent
Applications No. 2009-032494 filed on Feb. 16, 2009, No.
2009-051558 filed on Mar. 5, 2009, and No. 2010-026457 filed on
Feb. 9, 2010; the entire contents of all of which are incorporated
herein by reference.
FIELD
[0002] Embodiments described herein relate generally to an
electrical power storage system using hydrogen and a method for
storing electrical power using hydrogen.
BACKGROUND
[0003] In the case where there is a large difference in power
consumption between the daytime and the nighttime or in the case of
a power system with numerous interconnected wind power plants whose
power generating capability varies depending on the wind condition,
there is needed a power storage apparatus which stores surplus
power in the nighttime or the like and discharges electricity
during the daytime when the power goes short to correspond to a
peak load, so as to effectively utilize a power generation
facility. The most representative one is a pumped storage
hydroelectric plant. In this plant, water is pumped to an upper dam
during the nighttime to effectively store surplus power during the
nighttime, and power is generated with a hydraulic turbine
generator using the stored water in the daytime hours when a large
power is consumed, so as to correspond to the peak load during the
daytime.
[0004] The pumped storage hydroelectric plant has good
responsiveness as a large power generation facility, and thus
assumes the central role of equalizing loads of power systems.
However, the power storage technology using the pumped storage
hydroelectric plant is limited in geographical conditions such as
whether it is possible to use a river or seawater, whether it is
possible to build a dam, and so on. There is a further limitation
that it is not applicable unless the input/output capacity of the
system is 200 MW at the minimum.
[0005] As a relatively large power storage facility other than the
pumped storage hydroelectric plant, power storage apparatuses using
hydrogen are known. It is known that a power storage apparatus
which includes electrolyzing and power generating means having a
solid-oxide electrolyte and combines a steam electrolysis cell and
a fuel cell. A solid electrolyte fuel cell can generate power by
adding oxygen and hydrogen. Further, as backward reaction, it is
also possible to apply voltage to the added steam to electrolyze it
for obtaining oxygen and hydrogen. Utilizing this principle, steam
is electrolyzed by surplus power to produce hydrogen, and the
hydrogen is utilized to generate power when power is needed.
[0006] A common heat storage technique is known. It is known that
an apparatus such that waste heat at 200.degree. C. or lower is
stored in a latent heat storage material such as sodium acetate
3-hydrate or magnesium chloride 6-hydrate, and heat is exchanged
between the latent heat storage material and a heat medium for
utilizing the waste heat. A heat storage technique applied to solar
power generation is known, in which molten salts corresponding to
respective temperatures of 649.degree. C. or higher, 816.degree. C.
or higher, 927.degree. C. or higher, and 982.degree. C. or higher
are used as a heat storage material. It is known that a heat
storage unit in which a molten salt as a heat storage material is
filled in a porous ceramic container.
[0007] In power storage apparatuses using hydrogen, heat which is
generated mainly during power generation is utilized effectively,
and it is important how to supply heat required for electrolysis.
Heat obtained mainly during power generation is used for air
conditioning. However, in an air conditioner application, heat can
be supplied only in the vicinity, and demands for air conditioning
do not always match the generated heat amount. Thus, the heat
cannot always be utilized effectively. It is known that heat
generated during power generation is stored in a heat accumulator,
and the stored heat is used for generating hydrogen. Also in this
case, it cannot be said that use efficiency of heat generated
during power generation is always high.
[0008] Incidentally, in a power storage apparatus or a heat storage
apparatus, ceramic members are used which excel in heat resistance,
strength, toughness, and so on. Further, ceramic members are used
in various apparatuses as a heat resistant member, abrasion
resistant member, an abrasive, a precision machine member, and so
on. In recent years, application mainly of nonoxide-based ceramic
members of a silicon carbide (SiC), a silicon nitride
(Si.sub.3N.sub.4), and the like is in progress to semiconductor
manufacturing apparatus parts, parts for energy equipment of
nuclear energy or a gas turbine, space structural parts, automotive
parts such as engine parts and exhaust gas filters, heat exchanger
parts, pump parts, mechanical sealing parts, bearing parts, sliding
parts, and so on.
[0009] Ceramic members generally contract about 20% during
sintering, and hence it is difficult to fabricate large parts and
complicated shape parts with them. Accordingly, attempts have been
made to prepare a plurality of ceramic members and couple them
together to produce a large part or a complicated shape part. As a
method to join ceramic members together, there has been proposed a
method to join a plurality of ceramic members by using reaction
sintering of a silicon carbide.
[0010] It is known that a method to join a plurality of ceramic
members formed of a silicon carbide-silicon composite sintered body
or the like via a silicon carbide-silicon composite material layer
(joining layer). Also, after a plurality of ceramic members are
joined together with an organic resin-based adhesive, the joined
part is impregnated with molten silicon. The joining layer is
formed of silicon carbide particles, which are based on reaction
between carbon in the organic resin and the molten silicon, and a
silicon phase existing in interstices among the particles.
[0011] Further, after a plurality of ceramic members are joined
with an adhesive containing a silicon carbide powder, a carbon
powder, and an organic resin, the joined part is impregnated with
molten silicon. In this case, in addition to silicon carbide
particles based on the silicon carbide powder in the adhesive, the
joining layer contains silicon carbide particles based on reaction
between carbon contents in the carbon powder and the organic resin
and the molten silicon, and the silicon phase is made to exist in
interstices among these silicon carbide particles. In either case,
a thermosetting resin is used as the organic resin to be an
adhering component and a viscous component in the adhesive.
[0012] By the joining method described above, a free silicon phase
exists in interstices among the silicon carbide particles forming
the joining layer (silicon carbide-silicon composite material
layer), which improves denseness or mechanical properties of the
joining layer. Thus, joining strength among a plurality of ceramic
members can be enhanced. However, it is known that, since the
adhesive use a thermosetting resin, it is necessary to cure the
thermosetting resin by heat treatment when obtaining a shaped
product made by preliminarily joining a plurality of ceramic
members (a shaped product before being impregnated with molten
silicon). The thermosetting resin becomes soft once while being
heated, and thus it is possible that a displacement or the like
occurs in a joined part of the shaped product, making it unable to
keep its intended shape.
[0013] Therefore, so as to keep the shape of a preliminarily shaped
product or, in particular, the shape of a joined part by using an
adhesive during curing treatment for the thermosetting resin, it is
necessary to fix the preliminary shaped product with a jig. The jig
to fix the preliminary shaped product needs to be prepared
corresponding to the shapes and sizes of various types of parts,
and thus becomes a main cause to increase manufacturing costs and
the number of manufacturing processes of ceramic composite members
such as joined members. Further, even when the preliminary shaped
product is fixed with a jig, the thickness of the joined part may
be uncontrollable, and dispersion in thickness of the final joining
part may occur, which decreases material properties including
joining strength.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a block diagram schematically illustrating an
electrical power storage system using hydrogen according to a first
embodiment.
[0015] FIG. 2 is a perspective view illustrating an example of a
high-temperature heat storage device in the electrical power
storage system of the first embodiment.
[0016] FIG. 3 is cross-sectional views illustrating a first
structural example of a capsule used in the high-temperature heat
storage device illustrated in FIG. 2, where FIG. 3A is a
cross-sectional view illustrating a state before a first ceramic
member and a second ceramic member are joined, and FIG. 3B is a
cross-sectional view illustrating a state that the first ceramic
member and the second ceramic member are joined.
[0017] FIG. 4 is a cross-sectional view illustrating a second
structural example of a capsule used in the high-temperature heat
storage device illustrated in FIG. 2.
[0018] FIG. 5 is a cross-sectional view illustrating a third
structural example of a capsule used in the high-temperature heat
storage device illustrated in FIG. 2.
[0019] FIG. 6 is a block diagram schematically illustrating an
electrical power storage system using hydrogen according to a
second embodiment.
[0020] FIG. 7 is a block diagram schematically illustrating an
electrical power storage system using hydrogen a third
embodiment.
[0021] FIG. 8 is a block diagram schematically illustrating an
electrical power storage system using hydrogen according to a
fourth embodiment.
[0022] FIG. 9 is a cross-sectional view illustrating manufacturing
processes of a ceramic joined member (ceramic composite member)
according to an embodiment, where FIG. 9A is a cross-sectional view
illustrating a state that the first ceramic body and a second
ceramic body are joined with a viscous material, FIG. 9B is a
cross-sectional view illustrating a state that the viscous material
is made to be a porous body, and FIG. 9C is a cross-sectional view
illustrating a state that the first ceramic body and the second
ceramic body are joined by impregnating the porous body with molten
silicon.
DETAILED DESCRIPTION
[0023] According to one embodiment, there is provided an electrical
power storage system using hydrogen including a power generation
unit generating power using hydrogen and oxidant gas, an
electrolysis unit electrolyzing steam to generate hydrogen, a
hydrogen storage unit storing hydrogen generated by the
electrolysis and supplying the hydrogen to the power generation
unit during power generation, a high-temperature heat storage unit
storing first heat generated accompanying the power generation and
supplying the first heat to the electrolysis unit during the
electrolysis, and a low-temperature heat storage unit storing
second heat, which is exchanged in the high-temperature heat
storage unit and is lower than the temperature of the first heat
stored in the high-temperature heat storage unit, and generating
with the second heat the steam supplied to the electrolysis
unit.
[0024] According to another embodiment, there is provided a ceramic
joining material including a mixture containing a silicon carbide
powder having a mean particle diameter in the range of 0.5 .mu.m to
5 .mu.m, a carbon powder having a mean particle diameter in the
range of 0.3 .mu.m to 3 .mu.m and a room temperature setting resin
having viscosity and adhesiveness, and a curing agent of the room
temperature setting resin which cures the mixture, in which the
volume ratio of the silicon carbide powder to all the powder
components in the joining material is in the range of 18% to
60%.
[0025] Embodiments will be described with reference to the
drawings. Note that the same or similar components are denoted by
common numerals, and duplicated descriptions are omitted.
[0026] To begin with, a first embodiment of an electrical power
storage system will be described. FIG. 1 is a block diagram
schematically describing the structure of the electrical power
storage system using hydrogen according to the first embodiment.
The electrical power storage system (apparatus) 10 illustrated in
FIG. 1 includes a power/hydrogen converting device 11. The
power/hydrogen converting device 11 is an apparatus capable of
performing power generation and electrolysis of steam (generation
of hydrogen) while switching these operations over time.
Specifically, it is formed of a solid electrolyte fuel cell having
a solid-oxide electrolyte.
[0027] The solid electrolyte fuel cell combines a power generation
unit generating power using hydrogen and oxidant gas, and an
electrolysis unit electrolyzing steam. In FIG. 1, directions of
flows of electricity (power), air (oxygen), hydrogen, heat in a
power generation operating mode are denoted by black arrows, and
directions of flows of electricity (power), steam, heat, hydrogen
in an electrolysis operating mode are denoted by white arrows.
[0028] In the power generation operating mode, hydrogen is supplied
to a hydrogen electrode (fuel electrode) of the power/hydrogen
converting device (solid electrolyte fuel cell) 11, and oxidant gas
(oxygen or air containing oxygen) is supplied to an oxidant
electrode, thereby performing power generation. On the other hand,
in the electrolysis (hydrogen generation) operating mode, steam is
supplied to the hydrogen electrode side of the power/hydrogen
converting device (solid electrolyte fuel cell) 11 and power is
supplied simultaneously, thereby electrolyzing the steam to
generate hydrogen.
[0029] The electrical power storage system 10 includes a hydrogen
storage unit 12 storing hydrogen which is generated during the
electrolysis (hydrogen generation) operating mode. As the hydrogen
storage unit 12, for example, a hydrogen storage tank is used. The
hydrogen stored in the hydrogen storage unit 12 is supplied to the
hydrogen electrode (fuel electrode) of the power/hydrogen
converting device (solid electrolyte fuel cell) 11 during the power
generation operating mode.
[0030] The electrical power storage system 10 further includes a
high-temperature heat storage unit 13 storing high temperature heat
of 650.degree. C. to 1000.degree. C. generated in the
power/hydrogen converting device 11 during the power generation
operating mode. The high temperature heat stored in the
high-temperature heat storage unit 13 is supplied to the
power/hydrogen converting device 11 during the electrolysis
operating mode. Since steam electrolysis is heat absorbing
reaction, it is necessary to supply heat externally. Note that the
electrical power storage system 10 includes, although omitted from
illustration here, a low-temperature heat storage unit in addition
to the high-temperature heat storage unit 13. Details of the
high-temperature heat storage unit and the low-temperature heat
storage unit will be described later.
[0031] In the electrical power storage system 10, generally, for
example, steam electrolysis operation using power is performed
during the nighttime when power demands are low and hydrogen is
stored in the hydrogen storage unit 12. During the daytime when
power demands are high, the hydrogen stored in the hydrogen storage
unit 12 is used for performing a power generating operation. Heat
generated during the power generating operation is stored in the
high-temperature heat storage unit 13 through discharged steam or a
heat medium which exchanged heat with the discharged steam. In the
high-temperature heat storage unit 13, for example, heat of
650.degree. C. to 1000.degree. C. is stored.
[0032] During the electrolysis operation, water (steam) is supplied
to the hydrogen electrode side of the power/hydrogen converting
device (solid electrolyte fuel cell) 11. At this time, heat needed
for the electrolysis operation is discharged from the
high-temperature heat storage unit 13 via the steam or the heat
medium. The temperature of the steam or heat medium discharging
heat is 600.degree. C. to 1000.degree. C., for example. Hydrogen is
generated and discharged by electrolysis of steam on the hydrogen
electrode side, and this hydrogen is stored in the hydrogen storage
unit 12. Concurrently, oxygen is generated and discharged on the
oxygen electrode side.
[0033] A specific structural example of the high-temperature heat
storage unit 13 will be described with reference to FIG. 2. FIG. 2
is a perspective view illustrating an example of a heat storage
device forming the high-temperature heat storage unit 13 of the
electrical power storage system 10 of the first embodiment. The
high-temperature heat storage unit (heat storage device) 13
includes a plurality of capsules 14 in which a heat storage
material is encapsulated, and a heat storage container 15 housing
these capsules 14. The heat storage container 15 forms flow paths
for a heat medium fluid flowing around the capsules 14.
[0034] The capsules 14 are cylindrical containers for example, in
which a heat storage material (not illustrated) is encapsulated.
The heat storage material used for the high-temperature heat
storage unit 13 is one having a melting point to melt when storing
heat and solidify when releasing heat, and it is preferred to have,
for example, a melting point in the temperature range of
650.degree. C. to 1000.degree. C. with heat of solution of 200
kJ/kg or higher and specific heat of solid and liquid of 1 kJ/kgK
or higher. It is preferred that the capsules 14 have corrosive
resistance to the encapsulated heat storage material and
conductivity of heat of 650.degree. C. to 1000.degree. C. at 10
W/mK or higher.
[0035] During the power generating operation, steam at a high
temperature of 650.degree. C. to 1000.degree. C. for example
obtained by the heat generated in the power/hydrogen converting
device 11 or the heat medium fluid which exchanged heat with this
steam is introduced into the heat storage container 15 and flows
outside the capsules 14. Thus, the capsules 14 and the heat storage
material in a solid state encapsulated therein are heated. The heat
storage material is heated and melted, and changes from solid to
liquid. By utilizing latent heat during this phase transition from
solid to liquid, a large amount of heat can be stored in a
relatively small amount of heat storage material.
[0036] During the electrolysis operation, the high temperature heat
generated when the heat storage material in a liquid state
solidifies is transferred to the heat medium fluid via the capsules
14. By sending this high-temperature heat medium fluid to the
power/hydrogen converting device 11, necessary heat can be supplied
during the electrolysis operation. In this case, the heat medium
fluid such as steam is not in direct contact with a molten salt or
the like as the heat storage material and passes through the flow
paths outside the capsules 14.
[0037] As the heat storage material used for the high-temperature
heat storage unit 13, at least one selected from sodium chloride
(NaCl), potassium chloride (KCl), magnesium chloride (MgCl.sub.2),
calcium chloride (CaCl.sub.2), lithium fluoride (LiF), sodium
fluoride (NaF), lithium carbonate (Li.sub.2CO.sub.3), sodium
carbonate (Na.sub.2CO.sub.3), potassium carbonate
(K.sub.2CO.sub.3), and lithium hydroxide (LiH) is exemplified.
These may also be used in a mixture.
[0038] Depending on the type of the solid electrolyte of the
power/hydrogen converting device (solid electrolyte fuel cell) 11
or on operating conditions, the temperature of the heat discharged
during power generation differs. Thus, it is preferred that the
type of the heat storage material be selected depending on the
temperature of discharged heat and a heat storage capacity. By
using a single one of the above-described chemical compounds
(molten salts), it is possible to suppress variation in heat
storage/discharge characteristics, which becomes a problem in
relation with varying temperatures and enlargement of apparatus.
Thus, stability of the electrical power storage system 10 can be
improved.
[0039] It is preferred that the capsules 14 be formed of at least
one ceramic member selected from a silicon carbide (SiC) sintered
body, a silicon carbide-silicon (SiC--Si) composite sintered body,
a silicon carbide-based long fiber (SiC-long fiber (SiC long fiber
or the like)) composite material, a boron carbide (B.sub.4C)
sintered body, a silicon nitride (Si.sub.3N.sub.4) sintered body, a
boron nitride (BN) sintered body, and graphite (C). With the
capsules 14 formed of a ceramic member, heat transfer between the
heat storage material and the steam or heat medium fluid can be
improved, and weight reduction and size reduction of the heat
storage device as well as improvement in overall efficiency can be
achieved.
[0040] The capsules 14 are formed of a first and a second ceramic
member, at least one of which has a container shape. A specific
example of the ceramic members is as described above. FIG. 3
illustrates a first structural example of the capsules 14. The
capsule 14 illustrated in FIG. 3 has a first ceramic member 16
having a container shape and a second ceramic member 17 having a
lid shape. In addition, both the first ceramic member 16 and the
second ceramic member 17 may have a container shape. For
encapsulating the heat storage material in such a capsule 14, there
is a method as follows.
[0041] First, as illustrated in FIG. 3A, on an opening of the first
ceramic member 16 in which the heat storage material (not
illustrated) is housed, the second ceramic member 17 is disposed
via a joining material 18. As the joining material 18, a ceramic
precursor, a carbon adhesive, a silicon brazing material, or the
like is used. It is possible to apply a silicon carbide-silicon
composite body or the like to join the first ceramic member 16 and
the second ceramic member 17. Next, as illustrated in FIG. 3B, heat
treatment at temperatures corresponding to the joining material 18
is performed, thereby joining the first ceramic member 16 and the
second ceramic member 17 via a joining layer 19.
[0042] As the ceramic precursor, a polycarbosilane, a
polycarbosilazane, a polysilazane, a polyborosiloxane, a
polymetaloxane, or the like is used. After firing, these precursors
generate a ceramic layer formed of a Si--C-based ceramic, a
Si--C--N-based ceramic, a Si--O-based ceramic, a Si--B--C-based
ceramic, or the like as the joining layer 19. The carbon adhesive
contains a graphite powder and a resin or the like, and after
firing, a carbon layer is generated as the joining layer 19. As the
silicon brazing material, a foil, a paste, or the like is used, and
after firing (after brazing), these materials form a silicon layer
as the joining layer 19.
[0043] A joining method applying a silicon carbide-silicon
composite body is such that an adhesive containing carbon
components such as a carbon adhesive or an organic resin-based
adhesive is used as the joining material 18 to join the first
ceramic member 16 and the second ceramic member 17, and thereafter
heat treatment is performed with silicon (Si) being present to form
the joining layer 19 formed of a silicon carbide-silicon composite
body, thereby joining the first ceramic member 16 and the second
ceramic member 17. The silicon is supplied by, for example,
impregnating the joining layer (joining material 18) with molten
silicon. At this moment, a part of the molten silicon is actively
left, so as to form the joining layer 19 of a silicon
carbide-silicon composite body.
[0044] The heat storage material is encapsulated in the capsule 14
formed by joining the first ceramic member 16 and the second
ceramic member 17. When the heat storage material is encapsulated
in the capsule 14, if joining with high density and strength is not
made, there arises a problem such as a leak of the heat storage
material from the joining part. Further, when there is a difference
in thermal physical property between the ceramic members 16, 17
combining a heat transfer tube and the joining part, damage or the
like originating in the joining part occurs easily due to a thermal
cycle while storing/discharging heat. The joining layers 19
described above are all dense and strong, and also has excellent
thermal physical properties. Thus, it is possible to prevent a leak
of the heat storage material from the joining part, damage or the
like originating in the joining part, and the like. Therefore, a
heat storage device having stable heat storage/discharge
characteristics can be obtained.
[0045] It is preferred to apply a silicon carbide-silicon composite
body for the joining layer 19 between the first ceramic member 16
and the second ceramic member 17. It is preferred that the silicon
carbide-silicon composite body forming the joining layer 19 have a
structure having silicon carbide particles and a silicon phase
which exists continuously in a network form in interstices among
the silicon carbide particles. Such a silicon carbide-silicon
composite body can be formed by impregnating a porous body having
first silicon carbide particles and carbon with molten silicon,
causing the carbon in the porous body to react with the molten
silicon to generate second silicon carbide particles, and leaving
part of the molten silicon as the silicon phase.
[0046] The porous body having the first silicon carbide particles
and carbon is formed as follows for example. First, as the joining
material 18, there is prepared a viscous material containing a
silicon carbide powder to be the first silicon carbide particles, a
carbon powder, and a room temperature setting resin and a curing
agent thereof (joining material). It is preferred that the silicon
carbide powder have a mean particle diameter in the range of 0.5
.mu.m to 5 .mu.m. It is preferred that the carbon powder have a
mean particle diameter in the range of 0.3 .mu.m to 3 .mu.m.
Further, it is preferred that the volume ratio of the silicon
carbide powder to all the powder components in the viscous material
be in the range of 18% to 60%, and that the total mass ratio of the
silicon carbide powder and the carbon powder be in the range of 29%
to 55% of the entire viscous material. Reasons for the limitations
in these numbers will be described later.
[0047] Next, on the opening of the first ceramic member 16 in which
the heat storage material (not illustrated) is housed, the second
ceramic member 17 is disposed via the joining material 18 formed of
the above-described viscous material. A silicon foil or the like
can be used as a supply source of the molten silicon. When the
viscous material is applied on a joining face of the second ceramic
member 17, the silicon foil is disposed on a joining face of the
first ceramic member 16 in a manner to contact the viscous
material. Alternatively, when the viscous material is disposed
between the first ceramic member 16 and the second ceramic member
17, the silicon foil may be disposed around them in a manner of
wrapping them. When the viscous material and the silicon foil are
in contact, the molten silicon can be supplied sufficiently into
the porous body during heat treatment.
[0048] Next, the room temperature setting resin in the viscous
material is cured under room temperature and becomes a solidified
body. This results in preliminary joining of the first ceramic
member 16 and the second ceramic member 17, and thus spilling of
the heat storage material or the like can be prevented while being
transferred to a heat treatment furnace or handled. Subsequently,
by performing heat treatment to the solidified body of the viscous
material, a cured product of the room temperature setting resin is
carbonized. This causes the solidified body of the viscous material
to be porous. Then, the joining layer 19 formed of the silicon
carbide-silicon composite body is formed by impregnating such a
porous body with molten silicon, causing the carbon in the porous
body to react with the molten silicon to generate second silicon
carbide particles, and leaving part of the molten silicon as the
silicon phase. Note that details of conditions for forming the
joining layer 19 formed of the silicon carbide-silicon composite
body will be described later.
[0049] The shapes of the first and second ceramic members 16, 17
forming the capsules 14 are not limited to the shape illustrated in
FIG. 3. It is also effective to make the shapes of the joining
faces of the first ceramic member 16 having a container shape and
the second ceramic member 17 having a lid shape to be engaging
shapes as illustrated in FIG. 4 and FIG. 5. FIG. 4 and FIG. 5
illustrate joining faces such that projections are provided on the
joining face of the second ceramic member 17, and recesses
corresponding to the projections are provided on the joining face
of the first ceramic member 16. With such shapes of the joining
faces, a leak or the like of the heat storage material encapsulated
in the capsules 14 can be prevented more securely.
[0050] Regarding renewable energy such as solar energy and wind
power in a region where the weather changes largely, employing an
electrical power storage system having a solid electrolyte fuel
cell which performs power generation and steam electrolysis is
effective for improving power storage efficiency. Also regarding
renewable energy such as solar energy in a region where there is
less variation in nighttime power and weather, employing an
electrical power storage system having a solid electrolyte fuel
cell which performs power generation and steam electrolysis is
effective for improving power storage efficiency. The electrical
power storage system 10 of this embodiment stores heat of
650.degree. C. to 1000.degree. C. discharged during power
generation and uses this heat during electrolysis of steam, and
thus the stored heat can be utilized effectively. Therefore, the
overall efficiency of the electrical power storage system can be
increased largely.
[0051] Next, a second embodiment of an electrical power storage
system using hydrogen will be described. FIG. 6 is a block diagram
schematically illustrating the structure of the electrical power
storage system according to the second embodiment. The electrical
power storage system 20 illustrated in FIG. 6 includes a power
generation unit 21 which generates power using hydrogen and oxidant
gas, and an electrolysis unit 22 which electrolyzes steam. For the
power generation unit 21, for example, a solid electrolyte fuel
cell having a solid-oxide electrolyte is employed. For the
electrolysis unit 22, a steam electrolysis cell including a
solid-oxide electrolyte is employed. The steam electrolysis cell
forming the electrolysis unit 22 is a device which is separate from
the solid electrolyte fuel cell forming the power generation unit
21.
[0052] In the second embodiment, the part corresponding to the
power/hydrogen converting device 11 in the first embodiment is
separated into the fuel cell which performs power generation (power
generation unit 21) and the steam electrolysis cell which
electrolyzes steam (electrolysis unit 22), which are formed of
separated devices respectively. The other structure is the same as
that of the first embodiment. In the second embodiment, switching
of operating mode between power generation and steam electrolysis
as in the first embodiment is unnecessary, thereby allowing to
perform more flexible power generation and steam electrolysis.
Accordingly, it is possible to more flexibly correspond to
variation in power demand or the like, which contributes to stable
supply of power. Moreover, similarly to the first embodiment, the
overall efficiency of the electrical power storage system which
effectively utilizes heat can be improved.
[0053] Next, a third embodiment of an electrical power storage
system using hydrogen will be described. FIG. 7 is a block diagram
schematically illustrating the structure of the electrical power
storage system according to the third embodiment. The third
embodiment illustrates an electrical power storage system 30
including a high-temperature heat storage unit 13 and a
low-temperature heat storage unit 31. The electrical power storage
system 30 of the third embodiment includes the low-temperature heat
storage unit 31 in addition to the high-temperature heat storage
unit 13 of the first embodiment.
[0054] In the electrical power storage system 30 of the third
embodiment, heat generated in the power/hydrogen converting device
11 during power generation is stored in the high-temperature heat
storage unit 13 via steam or a heat medium which exchanged heat
with this steam. In the high-temperature heat storage unit 13, heat
of 650.degree. C. to 1000.degree. C. is stored. Further, heat of
100.degree. C. to 600.degree. C. after being exchanged in the
high-temperature heat storage unit 13 is stored in the electrical
power storage system 30 via steam or a heat medium which exchanged
heat with this steam.
[0055] During electrolysis of steam, steam is generated by
evaporating water with heat discharged from the low-temperature
heat storage unit 31, and this steam is supplied to the hydrogen
electrode side of the power/hydrogen converting device 11.
Moreover, heat needed during electrolysis of steam is supplied by
discharging from the high-temperature heat storage unit 13 via
steam or a heat medium. The temperature of the steam or heat medium
discharging heat is 600.degree. C. to 900.degree. C., for example.
Hydrogen is generated and discharged by electrolysis of steam on
the hydrogen electrode side of the power/hydrogen converting device
11, and this hydrogen is stored in the hydrogen storage unit 12.
Concurrently, oxygen is generated and discharged on the oxygen
electrode side.
[0056] For the low-temperature heat storage unit 31, a heat storage
device having a structure similar to that of the high-temperature
heat storage unit 13 illustrated in FIG. 2 is employed. As the heat
storage material used for the low-temperature heat storage unit 31,
it is preferred to use an organic matter or a molten salt having a
melting point in a temperature range of 100.degree. C. to
200.degree. C., with heat of solution of 150 kJ/kg or higher, and
specific heat of solid and liquid of 1 kJ/kgK or higher. Examples
of the organic matter forming such a heat storage material include
xylitol, erythritol, mannitol, sorbitol, alditol, urea, and the
like. Examples of the molten salt include aluminum chloride
(AlCl.sub.3), iron chloride (FeCl.sub.3), lithium hydroxide (LiOH),
sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium nitrite
(NaNO.sub.2), lithium nitrate (LiNO.sub.3), sodium nitrate
(NaNO.sub.3), potassium nitrate (KNO.sub.3), and the like.
[0057] Next, a fourth embodiment of an electrical power storage
system using hydrogen will be described. FIG. 8 is a block diagram
schematically illustrating the structure of the electrical power
storage system according to the fourth embodiment. The electrical
power storage system 40 of the fourth embodiment includes,
similarly to the second embodiment, a power generation unit (solid
electrolyte fuel cell including a solid-oxide electrolyte) 21 and
an electrolysis unit (steam electrolysis cell including a
solid-oxide electrolyte) 22 which is separate from the power
generation unit. The other structure is the same as that of the
third embodiment.
[0058] The electrical power storage system 40 of the fourth
embodiment has characteristics of both the second embodiment and
the third embodiment. In the fourth embodiment, switching of
operating mode between power generation and electrolysis as in the
third embodiment is unnecessary, thereby allowing to perform more
flexible power generation and electrolysis. Accordingly, it is
possible to more flexibly correspond to variation in power demand
or the like, which contributes to stable supply of power. Moreover,
since the low-temperature heat storage unit 31 is provided in
addition to the high-temperature heat storage unit 13 similarly to
the third embodiment, the overall efficiency of the electrical
power storage system which effectively utilizes heat improves
further.
[0059] The above-described embodiments exemplify the electrical
power storage system of the present invention, and the present
invention is not limited thereto. For example, the structure of the
low-temperature heat storage unit 31 in the third and fourth
embodiments may be one not similar to the high-temperature heat
storage unit 13 illustrated in FIG. 2. Extensions or modifications
can be made within the range of the technical idea of the present
invention, for example the structure of a latent heat storage
device can be applied to the low-temperature heat storage unit 31,
and such extended or modified embodiments are included in the
technical scope of the present invention.
[0060] Next, an embodiment of a ceramic joining material and a
manufacturing method of a ceramic composite member using the
ceramic joining material will be described. The manufacturing
method of a ceramic composite member (joining method of ceramic
members) according to this embodiment is applied to a forming
method of the capsules 14 (joining method of the first ceramic
member 16 and the second ceramic member 17) in the above-described
embodiments of the electrical power storage system, and specifies
specific conditions and the like in this application. However, the
ceramic joining material and the manufacturing method of the
ceramic composite member of this embodiment are not limited thereto
and are applicable to joining or repair of various ceramic
bodies.
[0061] The ceramic joining material of this embodiment includes a
first component formed of a mixture containing a silicon carbide
powder, a carbon powder, and a room temperature setting resin, and
a second component formed of a curing agent which cures the first
component (mixture) (curing agent which cures the room temperature
setting resin). The ceramic joining material as a viscous material
prepared by mixing the first component and the second component is
used for joining or repair of ceramic bodies. That is, as a mixture
(viscous material) of the first component and the second component,
the ceramic joining material is used for manufacturing a ceramic
joined member formed by joining a plurality of ceramic bodies or a
ceramic composite member such as a ceramic repaired member in which
a part of a ceramic body is repaired.
[0062] Examples of the ceramic bodies for which the ceramic joining
material is applied for joining or repair include molded bodies or
sintered bodies of silicide ceramics such as silicon carbides,
silicon nitrides, and complex chemical compounds mainly containing
them. Further, the material is also applicable to ceramics other
than the silicide ceramics and is effective for carbide ceramics
such as boron carbides and graphite. Specific examples of ceramic
bodies include a silicon carbide-carbon composite molded body, a
silicon carbide-silicon composite sintered body, a silicon carbide
sintered body, a silicon nitride sintered body, and graphite. The
ceramic joining material is particularly effective for silicon
carbide-based ceramic bodies.
[0063] The ceramic joining material of this embodiment forms a
silicon carbide (SiC)-silicon (Si) composite body through a shaping
process, a heat treatment process, an impregnation process of
molten silicon, and so on, which will be described later. The
SiC--Si composite body includes first SiC particles based on the
silicon carbide powder in the joining material, second SiC
particles generated by reaction between the carbon components
(porous carbon generated by performing heat treatment
(carbonization treatment) on a carbon powder and a cured product of
a room temperature setting resin) in the joining material and the
molten silicon, and a Si (free Si phase) filling interstices among
the first and second SiC particles. Such a SiC--Si composite body
forms a joining part which joins a plurality of silicon-based
ceramic bodies or a repair part for repairing a part of a
silicon-based ceramic body.
[0064] The first component of the ceramic joining material is
formed of a mixture containing a room temperature setting resin as
a component to add adhesiveness and viscosity, and the second
component is formed of a curing agent which cures the first
component (mixture). The room temperature setting resin and the
curing agent form a room temperature setting resin composition, for
which an epoxy-based resin composition or a phenol-based resin
composition having a room temperature setting property is used. The
room temperature setting resin composition is separated into two
components of a base resin, whose main component is the room
temperature setting resin, and a curing agent, which are mixed to
be used just before working with it. In the ceramic joining
material, for example, a silicon carbide powder, a carbon powder,
and the base resin of the room temperature setting resin
composition are mixed (first component) in advance, and then the
curing agent (second component) is blended therewith to be used for
joining or repairing ceramic bodies.
[0065] In the room temperature setting epoxy-based resin
composition, the base resin contains, as a main component of the
epoxy-based resin composition, an epoxy resin of bisphenol-A type,
bisphenol-F type, cresol-novolac type, phenol-novolac type, high
polymer type, epoxy polyol, or the like. In addition to the epoxy
resin, the base resin generally contains an inorganic filler of
silica, alumina, talc, clay, mica, quartz powder, titanium oxide,
calcium carbonate, or the like. In addition, the silicon carbide
powder and the carbon powder in the first component correspond to
part of the inorganic filler in the resin composition. Further, the
base resin may contain various fillers and additives, such as a
hardening accelerator, a coloring agent, a coupling agent, and the
like which are normally added to an epoxy-based resin composition,
as well as a solvent or the like for dilution. Therefore, the first
component of the joining material may contain fillers and
additives, such as an inorganic filler, a hardening accelerator, a
coloring agent, a coupling agent, and the like as well as a solvent
or the like for dilution, in addition to the room temperature
setting epoxy resin.
[0066] Examples of the curing agent in the room temperature setting
epoxy-based resin composition include an acid anhydride, a
polyamine, a polyamide, a novolac resin, an epichlorohydrin, and
the like. The amount of the curing agent (amount with respect to
the epoxy resin in the base resin) is set appropriately according
to its type and hardening reaction mechanism under room
temperature, and further a hardening degree of the viscous material
under room temperature, and so on. Such a curing agent of the room
temperature setting epoxy resin is used as the second component of
the joining material.
[0067] In the room temperature setting phenol-based resin
composition, the base resin contains, as a main component of the
phenol-based resin composition, a phenol resin such as a novolac, a
resole, or the like. In addition to the phenol resin, the base
resin generally contains an inorganic filler of silica, alumina,
talc, clay, mica, quartz powder, titaniumoxide, calcium carbonate,
or the like. Further, the base resin may contain various fillers
and additives, such as a hardening accelerator, a coloring agent, a
coupling agent, and the like which are normally added to a
phenol-based resin composition, as well as a solvent or the like
for dilution. Therefore, the first component of the joining
material may contain fillers and additives, such as an inorganic
filler, a hardening accelerator, a coloring agent, a coupling
agent, and the like as well as a solvent or the like for dilution,
in addition to the room temperature setting phenol resin.
[0068] Examples of the curing agent in the room temperature setting
phenol-based resin composition include an acid anhydride, a
polyamine, a polyamide, and the like. The amount of the curing
agent (amount with respect to the phenol resin in the base resin)
is set appropriately according to its type and hardening reaction
mechanism under room temperature, and further a hardening degree of
the viscous material under room temperature, and so on. Such a
curing agent of the room temperature setting phenol resin is used
as the second component of the joining material.
[0069] The ceramic joining material of this embodiment is such that
a silicon carbide powder and a carbon powder are mixed with the
base resin of the room temperature setting resin composition (first
component), and a curing agent (second component) is mixed with
this mixture to prepare a viscous material (mixture of the first
component and the second component) to be used. The ceramic joining
material has a resin component formed of a room temperature setting
resin (fluid resin component such as a liquid resin component), and
a powder component based on the silicon carbide powder and the
carbon powder. The powder component in the ceramic joining material
means the silicon carbide powder and the carbon powder, and does
not include a powder component blended in advance in the room
temperature setting resin.
[0070] The silicon carbide powder blended in the first component of
the ceramic joining material has a mean particle diameter in the
range of 0.5 .mu.m to 5 .mu.M. When the mean particle diameter of
the silicon carbide powder is smaller than 0.5 .mu.m, a
distribution state of respective components (carbon contents based
on the silicon carbide powder, the carbon powder, and the resin) in
a porous body formed by heat treating the mixture (viscous
material) of the first component and the second component and a
distribution state of components (the second SiC particles and the
Si phase) in the SiC--Si composite body formed by impregnating the
porous body with molten Si become non-uniform. On the other hand,
when the mean particle diameter of the silicon carbide powder is
larger than 5 .mu.M, the size of the Si phase tends to be too
large. In either case, it is not possible to increase the strength
of the SiC--Si composite body.
[0071] The carbon powder has a mean particle diameter in the range
of 0.3 .mu.m to 3 .mu.m. When the mean particle diameter of the
carbon powder is smaller than 0.3 .mu.m, flocculation occurs
easily, and the distribution state of the second SiC particles and
the Si phase in the SiC--Si composite body becomes non-uniform.
When the mean particle diameter of the carbon powder is larger than
3 .mu.m, a chalking phenomenon occurs easily, and the strength of
the SiC--Si composite body decreases. Here, the chalking phenomenon
is such that a dense SiC layer is formed on a surface side due to
volume increase during generation of SiC by reaction with molten
silicon, and permeation of the molten silicon to the inside is
hindered, resulting in that the carbon inside remains unchanged.
Further, when the mean particle diameter of the carbon powder is
too large, the mean diameter of the Si phase tends to be large,
leading to decrease or dispersion in strength of the SiC--Si
composite body forming the joining part or the repair part.
[0072] It is preferred that the ceramic joining material contain
the silicon carbide powder in the range of 18 volume % to 60 volume
% with respect to the total powder component. When the volume ratio
of the silicon carbide powder is lower than 18 volume %, the first
SiC particles which functions as aggregate in the SiC--Si composite
body become insufficient, and the distribution state of the second
SiC particles and the Si phase can easily become non-uniform. On
the other hand, when the volume ratio of the silicon carbide powder
is higher than 60 volume %, the Si phase in the SiC--Si composite
body becomes too large. In either case, there is a concern that the
strength of the SiC--Si composite body cannot be exhibited
sufficiently. It is preferred that the volume ratio of the silicon
carbide powder to the total powder component be in the range of 22%
to 56%.
[0073] It is preferred that the total content of the silicon
carbide powder and the carbon powder in the ceramic joining
material be in the range of 29 mass to 55 mass % of the entire
material. By applying such a content of the powder component (the
silicon carbide powder and the carbon powder), when the joining
part joining a plurality of ceramic bodies or the repair part for
repairing a part of a ceramic body are formed, it is possible to
obtain a viscous material (the mixture of the first component and
the second component of the ceramic joining material) by which
joining parts or repair parts of various shapes and sizes can be
easily shaped. That is, formability (workability) of the joining
part and the repair part with the ceramic joining material can be
increased.
[0074] When the total content of the powder component formed of the
silicon carbide powder and the carbon powder is higher than 55 mass
%, the mixture (viscous material) of the first component and the
second component of the ceramic joining material tends to be too
high. Further, when the total content of the powder component is
less than 29 mass %, conversely there is a concern that the
viscosity of the mixture (viscous material) of the first component
and the second component becomes too low. In either case,
workability (formability) of the mixture (viscous material) of the
first component and the second component decreases. It is more
preferred that the total content of the silicon carbide powder and
the carbon powder in the ceramic joining material be in the range
of 29 mass % to 40 mass %.
[0075] Further, when ceramic bodies to be joined or repaired are a
dense material like a sintered body, it is preferred to use the
ceramic joining material with a relatively large content of the
powder component (joining material whose content of the powder
component is on the 55 mass % side). Conversely, when the ceramic
bodies are porous like a molded body such as a green compact or the
like, it is preferred to use the ceramic joining material with a
relatively small content of the powder component (joining material
whose content of the powder component is on the 29 mass %
side).
[0076] When the powder component amount of the ceramic joining
material is relatively large (the content of the powder component
is on the 55 mass % side), the shape retention of the mixture
(viscous material) of the first component and the second component
becomes high, and it is easy to be joined to a ceramic body.
However, when the ceramic bodies are porous like a green compact, a
resin component (liquid component) is absorbed into the ceramic
bodies, and thus, for example, the ceramic bodies become difficult
to be joined together. In such a case, it is preferred to use the
ceramic joining material with a relatively small powder component
amount (the joining material whose content of the powder component
is on the 29 mass % side). With such a joining material, the
mixture (viscous material) of the first component and the second
component cut into recess portions on the surface of a green
compact, thereby improving the adhesiveness.
[0077] Regarding the ceramic joining material of this embodiment,
the viscous material prepared by mixing the first component and the
second component is given moderate viscosity based on the fluidity
(liquidity or the like) which the room temperature setting resin
has, the blending amount of the powder component, and the like, and
thus it can be shaped easily on a joining face or a repair face of
a ceramic body. Further, since the viscous material formed of the
mixture of the first component and the second component hardens
under room temperature, a predetermined shape required for the
joining part or the repair part can be maintained easily.
Therefore, by using the ceramic joining material of this
embodiment, it is possible to easily and precisely form the joining
part or the repair part on ceramic bodies of various shapes and
sizes, in particular, ceramic bodies forming a large structural
member or a complicated shape member.
[0078] Next, with reference to FIG. 9, a manufacturing method of a
ceramic composite member according to the embodiment will be
described. FIG. 9 is a cross-sectional view illustrating a
manufacturing method of a ceramic joined member to which the
manufacturing method is applied. Note that a manufacturing method
of a ceramic repaired member to which the manufacturing method is
applied is implemented by applying the same processes as the
manufacturing method of the joined member except that the mixture
(viscous material) of the first component and the second component
of the ceramic joining material is disposed on a repair position of
a ceramic body. Here, mainly the manufacturing method of the joined
member will be described.
[0079] FIG. 9 illustrates manufacturing processes of the ceramic
joined member according to the embodiment. First, as illustrated in
FIG. 9(a), a first and a second ceramic body 51, 52 are prepared as
members to be joined (base members). Here, although steps to join
the two ceramic bodies 51, 52 are described, there may be three or
more ceramic bodies as members to be joined (base members). When
this embodiment is applied to the manufacturing method of the
ceramic repaired member, a ceramic body which needs repair
(basically one ceramic body) is prepared.
[0080] It is preferred that the first and second ceramic bodies 51,
52 be molded bodies or sintered bodies of silicide ceramics such as
silicon carbides, silicon nitrides, and complex chemical compounds
mainly containing them or carbide ceramics such as graphite as
described above. It is preferred that the first and second ceramic
bodies 51, 52 be at least one selected from a silicon
carbide-carbon composite molded body, a silicon carbide-silicon
composite sintered body, a silicon carbide sintered body, a silicon
nitride sintered body, and graphite. The first and second ceramic
bodies 51, 52 may either be the same kinds of ceramic bodies or
different kinds of ceramic bodies. One of the first and second
ceramic bodies 51, 52 may be a molded body and the other may be a
sintered body.
[0081] A joining process of this embodiment is particularly
preferable for joining silicon carbide-carbon composite molded
bodies together, joining silicon carbide-silicon composite sintered
bodies together, and joining silicon carbide sintered bodies
together, and can obtain better results in such cases (results of
improvement in joining strength, strength in a ceramic joined
member (composite member) including a joining part, and the like).
This is the same when applying this embodiment to the manufacturing
method of the ceramic repaired member, and better results can be
obtained when it is applied to repair of a silicon carbide-silicon
composite sintered body or a silicon carbide sintered body.
[0082] Examples of the silicon carbide sintered body forming the
ceramic bodies 51, 52 include a pressure sintered body and a liquid
phase sintered body of an ordinary silicon carbide powder, a
reaction sintered body of a raw material powder containing a carbon
powder (for example, a mixed powder of a carbon powder and a
silicon carbide powder), and the like. The silicon carbide-carbon
composite molded body as the ceramic bodies 51, 52 is a green
compact of a mixed powder of a silicon carbide powder and a carbon
powder, and impregnating this with molten silicon results in the
silicon carbide-silicon composite sintered body.
[0083] The silicon carbide-carbon composite molded body is produced
by, for example, applying pressure formation such as powder
pressure molding or pressure casting to a mixed powder of a silicon
carbide powder and a carbon powder. For the pressure molding of the
mixed powder, metallic mold pressing, rubber pressing, cold
isostatic pressing, or the like is applied. When the pressure
casting is applied, slurry is prepared by dispersing the mixed
powder in water or organic solvent, and pressure casting this
slurry under an appropriate pressure. By applying such pressure
formation, a molded body having a moderate density (filling state
of powder) can be obtained.
[0084] As illustrated in FIG. 9A, a viscous material 53 is disposed
between the first and second ceramic bodies 51, 52. The viscous
material 53 is prepared by mixing a first component formed of a
mixture containing a silicon carbide powder, a carbon powder, and a
room temperature setting resin, and a second component formed of a
curing agent which cures the first component (mixture), and has a
silicon carbide powder 54, a carbon powder 55, and a room
temperature setting resin composition (mixture of a base resin and
a curing agent) 56. The room temperature setting resin in the
viscous material 53 is cured under room temperature, and a shaped
product 57 having a desired joined member shape is shaped. The
viscous material 53 becomes a solidified body adhering to joining
faces of the first and second ceramic bodies 51, 52 based on the
cured product of the room temperature setting resin cured in the
shaping process of the shaped product 57.
[0085] Thus, since the viscous material 53 can be solidified under
room temperature, it is possible to easily and precisely obtain the
shaped product 57 in which the first ceramic body 51 and the second
ceramic body 52 are joined via the solidified body of the viscous
material 53, without fixing the members to be joined with a jig or
the like. Further, it is not necessary to fix the shaped product 57
with a jig or the like in a heat treatment process or an
impregnation process of molten silicon thereafter, and thus
restrictions on shapes, sizes, and the like of the ceramic bodies
51, 52 and the joined member can be alleviated. That is, it is
possible to join the ceramic bodies 51, 52 of various shapes and
sizes by the solidified body of the viscous material 53.
[0086] Further, since the viscous material 53 can become a
solidified body under room temperature, it is possible to precisely
control, for example, the distance (joining distance) between the
first and second ceramic bodies 51, 52 as well as the thickness of
the joining part based on the solidified body of the viscous
material 53. The joining distance is based on the thickness of the
joining layer (the solidified body layer of the viscous material
53), and further corresponds to the thickness of the joining layer
(layer formed of a SiC--Si composite body) after impregnation with
molten silicon. The thickness of the joining part (joining layer)
affects the strength property and the like of the joined member
formed by joining the first ceramic body 51 and the second ceramic
body 52. In other words, by precisely controlling the thickness of
the joining part, it is possible to increase strength of the joined
member and reproducibility thereof.
[0087] Next, as illustrated in FIG. 9B, heat treatment is performed
on the shaped product 57 to carbonize the cured product of the room
temperature setting resin. The cured product of the room
temperature setting resin is disintegrated by the heat treatment
and becomes a carbon porous body 58, and this porous body 58 is in
a state that the silicon carbide powder 54 and the carbon powder 55
are dispersed inside. Based on such heat treatment (carbonization
treatment), the solidified body of the viscous material 53 is
turned into a porous body 59. It is preferred that the heat
treatment for carbonizing the cured product of the room temperature
setting resin be performed at temperatures in the range of
400.degree. C. to 1300.degree. C. When the heat treatment is
performed in a reduced pressure atmosphere, it is preferred to be 1
Pa or lower. By performing the heat treatment process under such
conditions, formability of the porous body 59 improves.
[0088] Thereafter, as illustrated in FIG. 9C, the porous body 59 is
impregnated with molten silicon to produce a ceramic joined member
61, in which the first and second ceramic bodies 51, 52 are joined
via the joining part formed of a SiC--Si composite body 60. The
impregnation process of molten silicon is performed by heating the
shaped product 57 having the porous body 59 to temperatures in the
range of 1400.degree. C. to 1500.degree. C. in a reduced pressure
atmosphere, and impregnating (vacuum impregnating) the porous body
59 in a heated state with molten silicon under the reduced pressure
atmosphere. It is preferred that the reduced pressure atmosphere
during the vacuum impregnation is at 1 Pa or lower.
[0089] When producing the ceramic repaired member, the viscous
material (mixture of the first component and the second component)
is applied to a repair position, for example a position where a
chip or a crack occurred, of a ceramic body formed of a silicon
carbide-silicon composite sintered body, a silicon carbide sintered
body, or the like, and the material is shaped. When the repair
position has a depth, the viscous material is filled in this
portion. Thereafter, the ceramic body to which the viscous material
is applied is subjected to the above-described heat treatment
process (carbonization process) and the impregnation process of
molten silicon, to thereby produce the ceramic repaired member
having a desired shape.
[0090] In the silicon carbide powder 54 existing in the solidified
body of the viscous material 53 made to be porous (porous body 59),
particles barely grow during the impregnation process of molten
silicon and hence become first SiC particles 62 having a particle
diameter substantially equal to the mean particle diameter of the
silicon carbide powder 54. The carbon component in the porous body
59, that is, carbon 58 originating from the carbon powder 55 and
the room temperature setting resin composition 56 contacts and
reacts with the molten silicon under high temperatures and
generates a silicon carbide (second SiC particles 63). Further, in
the porous body 59, the molten silicon remains partially, and this
molten silicon exists as a Si phase 64 in interstices among the
first and second SiC particles 62, 63.
[0091] When the ceramic bodies 51, 52 are silicon carbide-carbon
composite molded bodies or the like, the two molded bodies are
impregnated with molten silicon at the same time as the porous body
59. In the impregnation process of molten silicon, the two silicon
carbide-carbon composite molded bodies react with the molten
silicon and become silicon carbide-silicon composite sintered
bodies. That is, the ceramic joined member 61 is produced in which
the two silicon carbide-silicon composite sintered bodies, which
are reaction sintered in the impregnation process of molten
silicon, are integrated by the joining part formed of the SiC--Si
composite body 60 formed by allowing reaction simultaneously with
them. The silicon carbide-silicon composite sintered body has a
structure similar to the SiC--Si composite body 60 as the joining
part.
[0092] The joining part formed of the SiC--Si composite body 60
includes the first and second SiC particles 62, 63 and the Si phase
64 which exists continuously in a network form in interstices among
the particles. That is, the joining part has a dense structure in
which interstices among the SiC particles 62, 63 are filled with
the Si phase 64. When the repair part is formed of the SiC--Si
composite body, it has a similar structure. The second SiC
particles 63 based on reaction between a carbon component and
molten silicon have a mean particle diameter smaller than that of
the first SiC particles 62 based on the silicon carbide powder 54
blended in the viscous material 53. Based on the mean particle
diameters of the silicon carbide powder 54 and the carbon powder 55
and the mean particle diameters of the first and second SiC
particles 62, 63 based thereon, the SiC--Si composite body 60
having a uniform composite structure (in which the Si phase 64 with
a uniform size exists continuously in interstices among the SiC
particles 62, 63) is obtained.
[0093] Further, the SiC--Si composite body 60 has the first SiC
particles 62 of appropriate amount based on a blending amount (18
to 60% by volume ratio) with respect to the total powder component
of the silicon carbide powder 54 in the viscous material 53, that
is, the first SiC particles 62 having a relatively large mean
particle diameter. Based on the content of the first SiC particles
62 and the mean particle diameter of the SiC particles 62 or the
like based on the mean particle diameter of the silicon carbide
powder 54, the distribution states of the second SiC particles 63
in the SiC--Si composite body 60 and the Si phase 64 are uniformed,
and moreover, denseness of the SiC--Si composite body 60 also
improves. Also from these, it is possible to increase the strength
and reproducibility of the SiC--Si composite body 60.
[0094] In the SiC--Si composite body 60, it is preferred that the
Si phase 64 not only fill the interstices among the SiC particles
62, 63 but exist continuously in a network form in the interstices
among the SiC particles 62, 63. When the mesh structure of the Si
phase 64 is divided, it leads to occurrence of chalking phenomenon
(supply route of molten silicon is interrupted and reaction of
carbon stops), and the residual carbon amount increases, where
there is a concern that the strength of the joining part formed of
the SiC--Si composite body 60 decreases. In other words, it is
possible to obtain a dense and strong joining part by allowing the
Si phase 64 to exist continuously in interstices among the SiC
particles 62, 63.
[0095] In the above-described manufacturing process of the ceramic
joined member (composite member), it is preferred that the porous
body 59 have a mean pore diameter in the range of 0.5 .mu.m to 5
.mu.m. The mean pore diameter of the porous body 59 indicates a
mean value of diameters obtained using a mercury intrusion method
by assuming that they are columns. By impregnating the porous body
59 having such a mean pore diameter with molten silicon, it is
possible to improve strength properties (joining strength of the
SiC--Si composite body 60, strength of the SiC--Si composite body
60 itself, strength of the joined member 61 including the SiC--Si
composite body 60, and so on) based on the distribution state, the
mean diameter, and the like of the Si phase (free Si phase) 64 in
the SiC--Si composite body 60.
[0096] When the mean pore diameter of the porous body 59 is smaller
than 0.5 .mu.m, the supply route of the molten silicon is
interrupted which can lead to increase in residual carbon amount,
and a crack can easily occur due to volume expansion when a silicon
carbide is generated from carbon. When the mean pore diameter of
the porous body 59 is larger than 5 .mu.m, the amount of the Si
phase 64 increases. Any of these decreases the strength of the
SiC--Si composite body 60. Further, when the mean pore diameter of
the porous body 59 is too large, a crack or the like can easily
occur before impregnation with molten silicon, and manufacturing
yields and strength of the ceramic joined member 61 decrease.
[0097] Further, it is preferred that the Si phase 54 has a mean
diameter in the range of 0.2 .mu.m to 2 .mu.m. The mean diameter of
the Si phase 64 corresponds to the mean distance among the SiC
particles 62, 63. The mean diameter of the SiC phase 64 indicates a
value obtained as follows. First, the ceramic joined member 61
having the SiC--Si composite body 60 is heated to 1600.degree. C.
under a reduced pressure to remove free Si in the SiC--Si composite
body 60. The mean diameter of the Si phase 64 indicates a mean
value of diameters obtained by assuming the diameters of small
holes formed by removing free Si as columns using a mercury
intrusion method. This value matches results of cross-section
observation of the minute structure of SiC--Si composite body 60
with a metallurgical microscope or SEM.
[0098] When the mean diameter of the Si phase 64 is small, this
means that the Si phase 64 with low strength is miniaturized.
[0099] Further, this also means that the Si phase 64 is distributed
homogeneously in interstices among the SiC particles 62, 63. The
interstices among the SiC particles 62, 63 are filled evenly with
the Si phase 64. By thus controlling the mean diameter of the Si
phase 64 to be in the range of 0.2 .mu.m to 2 .mu.m, strength of
the joining part formed of the SiC--Si composite body 60 and
further strength as the ceramic joined member 61 including the
joining part can be increased with good reproducibility.
[0100] When the mean diameter of the Si phase 64 is larger than it
becomes close to a state that the Si phase 64 with low strength is
segregated, and the influence of the Si phase 64 on strength of the
SiC--Si composite body 60 becomes large. Therefore, strength of the
SiC--Si composite body 60 and strength of the ceramic joined member
61 decrease easily. When the mean diameter of the Si phase 64 is
smaller than 0.2 .mu.m, it is difficult to maintain the continuous
structure in a network form. Accordingly, pores or free carbon can
occur easily in the SiC--Si composite body 60, and dispersion in
strength of the joining part can easily occur. This is similar when
a repair part is formed of a SiC--Si composite body.
[0101] The mean diameter of the Si phase 64 can be controlled based
on the mean pore diameter of the porous body 59 before impregnation
with molten silicon and the mean particle diameters of the silicon
carbide powder 54 and the carbon powder 55 blended in the viscous
material 53. That is, by using the silicon carbide powder 54 having
a mean particle diameter in the range of 0.5 .mu.m to 5 .mu.m and
the carbon powder 55 having a mean particle diameter in the range
of 0.3 .mu.m to 3 .mu.m, and controlling the mean pore diameter of
the porous body 59 to be in the range of 0.5 .mu.m to 5 .mu.m, the
Si phase 64 which is minute and homogeneous (for example, the Si
phase 64 with a mean diameter in the range of 0.2 .mu.M to 2 .mu.m)
can be obtained.
[0102] In the manufacturing process of the ceramic composite
member, it is preferred that the impregnation process of molten
silicon be performed at temperatures in the range of 1400.degree.
C. to 1500.degree. C. It is preferred that the reduced pressure
atmosphere for impregnating molten silicon is at 1 Pa or lower. By
performing the impregnation process of molten silicon under such
conditions, an impregnation characteristic of molten silicon and
formability of the SiC particles 63 improve, and minute pores
(micro-pores or nano-pores) in the Si phase 64 can be decreased
significantly. Therefore, strength of the SiC--Si composite body 60
and reproducibility thereof can be increased.
[0103] In the manufacturing process of the ceramic joined member 61
in this embodiment, when two ceramic bodies 51, 52 are joined with
the viscous material 53, they can be cured in a state that the
joining part is shaped in a predetermined form. Thus, it is
applicable to a large structural member, a complicated shape part,
and the like and the precision of shape of the joining part can be
increased. Therefore, it is possible to obtain a joining part in
which dispersion in strength and material properties such as
thermal properties are suppressed.
[0104] With the above-described joining part, in addition to
improvement in its material properties, it is possible to improve
material properties of the ceramic joined member 61 having the
joining part and reproducibility thereof. Since it is unnecessary
to fix members to be joined with a jig or the like, manufacturing
costs and the number of manufacturing steps of the ceramic joined
member 61 can be reduced. Note that it is not intended to prohibit
use of a jig or the like when the shapes of joined members are
complicated or when there are many joining positions.
[0105] Further, in the manufacturing process of the ceramic joined
member 61, the joining part formed of the SiC--Si composite body 60
excels not only in joining strength with respect to the ceramic
bodies 51, 52 but in its strength and reproducibility thereof.
Therefore, a plurality of ceramic bodies 51, 52 can be joined with
high strength, and strength of the ceramic joined member 61 can be
increased with good reproducibility. These make it possible to
provide the ceramic joined member 61 with high strength at low
cost, which is preferable for complicated shapes and large
structural members and parts. Further, this is also the same when
the manufacturing process of this embodiment is applied to
production of a ceramic repaired member, and increase in strength
of ceramic repaired members, improvement in precision of shape,
cost reduction, and so on can be achieved.
[0106] In the above-described composite members such as the ceramic
joined member 61 and the ceramic repaired members, mechanical
properties such as strength can be increased with good
reproducibility, and thus they are applicable to various members
and parts which are required to have high strength. They contribute
largely to increase in strength in particular of large structural
objects, complicated shape parts, and the like. The ceramic
composite member can be applied to various apparatus parts and
apparatus members such as semiconductor manufacturing apparatus
jigs, semiconductor related parts (heat sinks, dummy wafers, and
the like), high-temperature structural members for gas turbine,
high-temperature members for heat accumulator, structural members
for space and aerial use, mechanical sealing members, brake
members, sliding parts, mirror parts, pump parts, heat exchanger
parts, chemical plant components, and the like. In particular, the
ceramic composite member is used preferably for apparatus parts and
members which are required to have high strength.
[0107] Next, specific examples and evaluation results thereof will
be described.
(Viscous Materials 1 to 6)
[0108] Viscous materials 1 to 6 were produced as follows. First, as
the room temperature setting resin composition, an epoxy-based
resin composition and a phenol-based resin composition which have a
room temperature setting property were prepared. To the base resin
of each room temperature setting resin composition illustrated in
Table 1, a silicon carbide powder having a mean particle diameter
in the range of 0.5 .mu.m to 5 .mu.m and a carbon powder having a
mean particle diameter in the range of 0.3 .mu.m to 3 .mu.m were
added and mixed. The mean particle diameters of the silicon carbide
powder and the carbon powder, the volume ratio of the silicon
carbide powder in the viscous material, and the total mass ratio of
the silicon carbide powder and the carbon powder are as illustrated
in Table 1.
[0109] To each mixture of the above-described base resin of the
room temperature setting resin composition, the silicon carbide
powder, and the carbon powder, the curing agent of the room
temperature setting resin composition was added and mixed
sufficiently, thereby preparing viscous materials 1 to 6. Note that
the curing agent of the room temperature setting resin composition
was mixed just before the viscous material is applied in the
manufacturing process of the ceramic composite member (for joined
members, just before disposing between joining faces of the ceramic
bodies, and for repaired members, just before disposing on a part
of a ceramic body) of examples 1 to 15, which will be described
later. Specific structures of the viscous materials 1 to 6 are as
illustrated in Table 1.
TABLE-US-00001 TABLE 1 Powder component Silicon carbide Carbon
Resin powder powder component Mean Mean (room particle Volume
particle temperature diameter ratio diameter Total mass setting
resin) (.mu.m) (%) (.mu.m) ratio (%) Viscous Epoxy resin 0.5 18 0.3
29 material 1 Viscous Epoxy resin 1 22 1 44 material 2 Viscous
Epoxy resin 2 40 1 47 material 3 Viscous Phenol resin 1 27 0.8 33
material 4 Viscous Phenol resin 2 45 1.5 47 material 5 Viscous
Phenol resin 5 60 3 55 material 6
Example 1
[0110] The silicon carbide powder having a mean particle diameter
of 0.8 .mu.m and the carbon powder (carbon black) having a mean
particle diameter of 0.4 .mu.m were mixed with a mass ratio of 10:3
(=SiC:C). After this mixed powder was mixed with an appropriate
amount of organic binder and thereafter it was dispersed in a
solvent, thereby preparing slurry. This slurry was filled into a
forming die using a pressure casting device while applying a
pressure. In this manner, two SiC-C composite molded bodies (green
compacts) were produced.
[0111] Next, after the viscous material 1 in Table 1 was disposed
between joining faces of the two SiC-C composite molded bodies, the
room temperature setting resin composition was cured to make a
shaped product having a desired joined member shape. This shaped
product was heated to a temperature of 1000.degree. C. in a
nitrogen or argon atmosphere, so as to carbonize the cured product
of the room temperature setting resin composition. In this
carbonization treatment, the solidified body of the viscous
material becomes a porous body. The mean pore diameter of the
porous body was 1.0 .mu.m. Thereafter, the shaped product in which
the two molded bodies are connected by the porous body was heated
to a temperature of 1450.degree. C. in a reduced pressure
atmosphere at 1 Pa or lower, and meanwhile the two molded bodies
and the porous body forming the joining part were impregnated with
molten silicon.
[0112] Next, in the impregnation process of molten silicon, the two
molded bodies were made to react with molten silicon, so as to make
SiC--Si composite sintered bodies, and they were joined with the
SiC--Si composite body which is a product of reaction of the porous
body and the molten silicon. Regarding the ceramic joined member
obtained in this manner, after the surface of the joining part
formed of the SiC--Si composite body was polished, the minute
structure was observed with an electron microscope. As a result, it
was recognized that the joining part has a structure in which the
Si phase exists continuously in a network form in interstices among
the SiC particles. The mean diameter of the Si phase was 0.7 .mu.m.
Such a ceramic composite member was subjected to property
evaluation, which will be described later.
Example 2
[0113] Two SiC-C composite molded bodies produced similarly to
example 1 were heated to a temperature of 600.degree. C. and held
in an inert gas atmosphere, so as to remove the organic binder. The
molded body after being degreased was heated to a temperature of
1450.degree. C. in a reduced pressure atmosphere at
1.times.10.sup.-1 Pa, and the molded body keeping this heated state
was impregnated with molten silicon. By causing reaction sintering
of the molded body in the impregnation process of molten silicon
(generation of SiC and densification by the Si phase), two SiC--Si
composite sintered bodies were produced.
[0114] Next, after the viscous material 2 in Table 1 was disposed
between joining faces of the two SiC--Si composite sintered bodies,
the room temperature setting resin composition was cured to make a
shaped product having a desired joined member shape. This shaped
product was heated to a temperature of 800.degree. C. in an inert
atmosphere, so as to carbonize the cured product of the room
temperature setting resin composition. In this carbonization
treatment, the solidified body of the viscous material becomes a
porous body. The mean pore diameter of the porous body was 0.8
.mu.m. Thereafter, the shaped product in which the two sintered
bodies are connected by the porous body was heated to temperatures
of 1400.degree. C. to 1500.degree. C. in a reduced pressure
atmosphere at 1 Pa or lower, and meanwhile the porous body forming
the joining part were impregnated with molten silicon.
[0115] Next, in the impregnation process of molten silicon, the two
SiC--Si composite sintered bodies were joined with the SiC--Si
composite body which is a product of reaction of the porous body
and the molten silicon. Regarding the ceramic joined member
obtained in this manner, after the surface of the joining part
formed of the SiC--Si composite body was polished, the minute
structure was observed with an electron microscope. As a result, it
was recognized that the joining part has a structure in which the
Si phase exists continuously in a network form in interstices among
the SiC particles. The mean diameter of the Si phase was 0.5 .mu.m.
Such a ceramic composite member was subjected to property
evaluation, which will be described later.
Examples 3 to 10
[0116] As members to be joined, there were prepared SiC-C composite
molded bodies, SiC--Si composite sintered bodies, SiC sintered
bodies by powder sintering method, and Si.sub.3N.sub.4 sintered
bodies. They were joined based on combinations illustrated in Table
2 to produce ceramic joined members. The joining process was
performed similarly to examples 1, 2. Viscous materials used for
joining are as illustrated in Table 2. Table 3 illustrates
structures of joining parts. All the joining parts of the
respective ceramic joined members had a structure in which a Si
phase exists continuously in a network form in interstices among
SiC particles. Each of the ceramic joined members was subjected to
property evaluation, which will be described later.
Comparative Example 1
[0117] A silicon foil was sandwiched between two SiC--Si composite
sintered bodies produced similarly to example 2, and they were
fixed by a jig. Thereafter, they were heated to temperatures at
which the silicon foil melts, so as to join them. A ceramic joined
member obtained in this manner was subjected to property
evaluation, which will be described later.
Comparative Example 2
[0118] On joining faces of two SiC--Si composite molded bodies
produced similarly to example 1, slurry prepared by dispersing a
silicon carbide powder, a carbon powder, and the like in a solvent
was applied to join them, and they were fixed with a jig.
Thereafter, they were impregnated with molten silicon similarly to
example 1. A ceramic joined member obtained in this manner was
subjected to property evaluation, which will be described
later.
TABLE-US-00002 TABLE 2 Joining Ceramic body 1 Ceramic body 2
material Example 1 SiC--C composite SiC--C composite Viscous molded
body molded body material 1 Example 2 SiC--Si composite SiC--Si
composite Viscous sintered body sintered body material 2 Example 3
SiC--C composite SiC--C composite Viscous molded body molded body
material 3 Example 4 SiC--C composite SiC--C composite Viscous
molded body molded body material 4 Example 5 SiC sintered body SiC
sintered body Viscous material 5 Example 6 SiC sintered body SiC
sintered body Viscous material 6 Example 7 SiC--Si composite SiC
sintered body Viscous sintered body material 2 Example 8 SiC--C
composite SiC--Si composite Viscous molded body sintered body
material 3 Example 9 Si.sub.3N.sub.4 sintered body Si.sub.3N.sub.4
sintered Viscous body material 4 Example 10 Si.sub.3N.sub.4
sintered body Si.sub.3N.sub.4 sintered Viscous body material 5
Comparative SiC--Si composite SiC--Si composite Silicon foil
Example 1 sintered body sintered body Comparative SiC--C composite
SiC--C composite Slurry Example 2 molded body molded body
[0119] Measurement of joining strength (4-point bending
measurement) of the respective ceramic joined members according to
examples 1 to 10 and Comparative Examples 1 and 2 was conducted in
accordance with JIS R 1624. Results are illustrated in Table 3.
Table 3 illustrates mean pore diameters of porous bodies formed in
the course of manufacturing the ceramic joined members, as well as
mean diameters of Si phases in the final ceramic joined members.
Further, applicable ranges of manufacturing processes of the
examples are studied. One applicable to a large structural member,
a complicated shape part, or the like is marked "Yes", and one
which is practically difficult to apply is marked "No".
TABLE-US-00003 TABLE 3 Joining part Mean pore Mean Bending diameter
(.mu.m) of diameter of strength Applicable porous layer Si phase
(.mu.m) (MPa) range Example 1 1.0 0.7 600-650 Yes Example 2 0.8 0.5
700-750 Yes Example 3 0.5 0.2 850-900 Yes Example 4 1.5 0.9 550-600
Yes Example 5 2.5 1.5 400-450 Yes Example 6 4.0 2.5 350-400 Yes
Example 7 2.0 1.2 600-700 Yes Example 8 0.7 0.4 750-800 Yes Example
9 3.0 1.8 400-450 Yes Example 10 0.9 0.6 650-700 Yes Comparative --
-- 80 No Example 1 Comparative -- 10 100 No Example 2
[0120] As is clear from Table 3, it can be seen that the ceramic
joined members of examples 1 to 10 all excel in mechanical
properties such as joining strength, as compared to Comparative
Examples 1 and 2. It was recognized that the joining part has
properties equivalent to those of the SiC--Si composite sintered
body or the like of the base member. Further, it was recognized
that the joining parts according to examples 1 to 10 also excel in
thermal properties such as heat conductivity. Note that the heat
conductivity was measured in accordance with JIS R 1611. Further,
examples 1 to 10 can be applied to members and parts of various
shapes and sizes. Regarding the sizes, it was recognized that they
are applicable to large structural members of meter-class size.
[0121] In Comparative Example 1, the members must be fixed with a
jig or the like so as to keep the joined shape and prevent the
sandwiched silicon foil from falling off while being heated.
Further, heating must be performed in a state that melted silicon
would not drip off. Accordingly, application to parts of various
shapes and sizes, particularly to large structural members and
complicated shape parts is difficult. In a state of being joined
with the slurry of Comparative Example 2 and dried, members have
almost no strength, and thus application of the manufacturing
process of Comparative Example 2 to parts of various shapes and
sizes, particularly to large structural members and complicated
shape parts is difficult.
Example 11
[0122] A SiC--Si composite sintered body was produced similarly to
example 2, and a cutout was formed thereon for forming a repair
part. The size of the cutout was 20 mm. In the cutout of this
SiC--Si composite sintered body, the viscous material 2 of Table 1
was applied and filled, and thereafter the room temperature setting
resin composition was cured. This SiC--Si complex sintered body was
heated to a temperature of 1000.degree. C. in an inert atmosphere
to carbonize the cured product of the room temperature setting
resin composition. The solidified body of the viscous material
becomes a porous body through this carbonization treatment. The
mean pore diameter of the porous body was 0.5 .mu.m to 2.0 .mu.m.
Thereafter, the SiC--Si composite sintered body was heated to a
temperature of 1450.degree. C. in a reduced pressure atmosphere at
1 Pa or lower, and meanwhile the porous body forming the repair
part was impregnated with molten silicon.
[0123] In the impregnation process of molten silicon, the cutout of
the SiC--Si composite sintered body was repaired with the SiC--Si
composite body which is the product of reaction between the porous
body and the molten silicon. Regarding the ceramic repaired member
obtained in this manner, after the surface of the repair part
formed of the SiC--Si composite body was polished, the minute
structure was observed with an electron microscope. As a result, it
was recognized that the repair part has a structure in which the Si
phase exists continuously in a network form in interstices among
the SiC particles. The mean diameter of the Si phase was 0.2 .mu.m
to 1.2 .mu.m. Strength of this ceramic repaired member was
measured, and it was recognized that it has strength equivalent to
that of a SiC--Si composite sintered body which does not have a
repair part.
Examples 12 to 15
[0124] As members to be repaired, there were prepared a SiC--Si
composite sintered body, a SiC--Si composite molded body, and SiC
sintered bodies by powder sintering method. They were repaired
based on combinations illustrated in Table 4 to produce ceramic
repaired members. The repairing process was performed similarly to
example 11. Viscous materials used for repair are as illustrated in
Table 4. Results of measuring strength of each ceramic repaired
member are illustrated in Table 5. Table 5 also illustrates
structures of the repair parts.
TABLE-US-00004 TABLE 4 Ceramic body Repair material Example 11
SiC--Si composite Viscous material 2 sintered body Example 12 SiC
sintered body Viscous material 2 Example 13 SiC--C composite
Viscous material 2 molded body Example 14 SiC--Si composite Viscous
material 5 sintered body Example 15 SiC sintered body Viscous
material 5
TABLE-US-00005 TABLE 5 Repair part Mean pore Mean diameter Bending
diameter (.mu.m) of of Si phase strength porous layer (.mu.m) (MPa)
Example 11 0.5-2.0 0.2-1.2 600-900 Example 12 1.0-4.0 0.6-2.5
350-600 Example 13 0.5-2.0 0.2-1.2 600-900 Example 14 0.8-1.5
0.5-0.9 550-750 Example 15 2.0-5.0 1.2-2.0 350-600
[0125] As is clear from Table 5, all the ceramic repaired members
in which repair parts are formed with a SiC--Si composite body have
strength equivalent to that of a sintered body having no repair
part, and effectiveness of the repair parts formed of a SiC--Si
composite body was recognized. Further, the viscous materials used
as a repairing material can be solidified during molding, and thus
it is possible to increase the shape precision of a repair part.
Therefore, reliability and repair yields of repaired ceramic
members improve.
[0126] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
inventions.
* * * * *